Re: [PATCH 2/2] replace several uses of the anon namespace with GCC_FINAL

[Richard Sandiford <richard.sandiford@arm.com>]

Jeff Law <law@redhat.com> writes:
> On 08/10/2015 06:05 AM, tbsaunde+gcc@tbsaunde.org wrote:
>> From: Trevor Saunders <tbsaunde+gcc@tbsaunde.org>
>>
>> Hi,
>>
>> In many places gcc puts classes in the anon namespace so the compiler can tell
>> they do not get inheritted from to enable better devirtualization.  However
>> debugging code in the anon namespace can be a pain, and the same thing can be
>> accomplished more directly by marking the classes as final.  When
>> bootstrapping
>> stage 3 should always be built in C++14 mode now, and of course will always be
>> newer than gcc 4.7, so these classes will always be marked as final there.
>> AIUI cross compilers are supposed to be built with recent gcc, which I would
>> tend to think implies newer than 4.7, so they should also be built with these
>> classes marked as final.  I believe that means in all important cases
>> this works just as well as the anon namespace.
>>
>> bootstrapped + regtested on x86_64-linux-gnu, ok?
>>
>> Trev
>>
>>
>> gcc/ChangeLog:
>>
>> 2015-08-10  Trevor Saunders  <tbsaunde@tbsaunde.org>
>>
>> 	* compare-elim.c, dce.c, dse.c, gimple-ssa-isolate-paths.c,
>> 	gimple-ssa-strength-reduction.c, graphite.c, init-regs.c,
>> 	ipa-pure-const.c, ipa-visibility.c, ipa.c, mode-switching.c,
>> 	omp-low.c, reorg.c, sanopt.c, trans-mem.c, tree-eh.c,
>> 	tree-if-conv.c, tree-ssa-copyrename.c, tree-ssa-dce.c,
>> 	tree-ssa-dom.c, tree-ssa-dse.c, tree-ssa-forwprop.c,
>> 	tree-ssa-sink.c, tree-ssanames.c, tree-stdarg.c, tree-tailcall.c,
>> 	tree-vect-generic.c, tree.c, ubsan.c, var-tracking.c,
>> 	vtable-verify.c, web.c: Use GCC_FINAL instead of the anonymous
>> namespace.
> OK.

I was hoping someone else was going to speak up since I seem
to have been posting a few negative messages recently, but I think
this is really a step in the wrong direction.  I think the code
was using anonymous namespaces in exactly the way they were
intended to be used.

We don't want to forbid the use of "static" and instead force every
file-local function and variable into the global namespace.  Why should
classes be any different?  Anonymous clases are a commonly-used feature,
so if there's a specific problem with debugging them, I think it would
be better to fix gdb (or whatever) rather than work around the problem
like this.

Thanks,
Richard